John t. George marsh. Help on Ristance and ohms

Have 64inch batt cable. On ih. Supermta. Have good meter have used to check continuity. Amps and volts. Never learned to measure ohms and restiance. What belies on meter. Show good and bad

A battery cable no matter what and no matter what you set your ohm meter at should give you a ZERO ohm reading since a battery cable is just a very big heavy duty wire. It you get any thing but zero it is bad or your meter is not reading as it should or has weak batteries in it. Ya not John or Geo but I am a former Navy E.T. and know me ohms as in tell me what this means. Bad Boys Rape Our Young Daughters But Violet Give Willingly. Hint has to do with read OHMS

Old.............That is how you remember resistor color codes!

girls

Youse forgot "GET SOME NOW". Dang kids...

Yes the green band is for girls. There is no "D" color on the bands. I gues every "girl" is some man's daughter.

You are in deep trouble if you break the Ohm's law!

Bill, not exactly sure what you want to measure with your volt meter. Call me. If you lost my number, I'll leave my email open and send it to you. I'll walk you through what ever you are trying to do over the phone.
George

Old, Change Daughtersd to girls or the colors won't be right.

You will not be able to accurately measure the resistance of a battery cable using the ohms scale of a typical multimeter. To measure down in the milliohm range you need to do a four-wire measurement, which typically is only supported by laboratory type instruments.

Let's back off a bit. What is it you really want to accomplish? Since you're dealing with a battery cable, I'm going to make a wild guess that you want to know if the cable is "good" or "bad". Well, what constitutes good/bad? The answer ISN'T resistance! It's voltage drop! All resistance is is the relationship between current and voltage. If you don't know what the current demand is for your starter, how can you know what's an acceptable resistance for the cable? You can't. But measuring the voltage drop is going to tell you if the cable is up to the job, and you don't actually need to know the current.

What you do is to pull the coil wire on your vehicle. Set your meter on volts, then measure the voltage between the cable ends while an assistant cranks the starter. I'm not sure what the acceptable range is for voltage drop, but I'd be concerned if it was greater than one volt on a 12 volt system, or half a volt on a six volt system. Personally I would want it to be much less than that, maybe a tenth of a volt from battery terminal to starter terminal.

Good morning neighbor, I got your call but we got home late and packing for Florida today:

I'm more familiar with olddddddd analog meters like my trusty reliable Simpson 260, but heres some info which may help:

1) There ought to be an R or Ohms or Resistance setting of some sort on the face of the meter. If a digital meter the range setting may???? be automatic (just an R and it sets its own range automatically) ...... If its an Analog it may have like Rx1 and Rx10 and Rx100 so if youre on Rx1 and the face reads 10 ohms its 10 ohms but if on Rx100 if it reads 10 that means its 1000 ohms.

2) Theres NO POLARITY when reading ohms, its just the resistance through an item regardless which lead (red or black) is connected to the ends of the item.

3) DO NOT try to read ohms when voltage is hot on an item and YOU SHOULD disconenct all other wires into and out of an item when measuring cuz the meter may read some other current path.

4) Remember OHMS is resistance THROUGH an item, end to end, copper wire and battery cables etc (extreme good conductors) should show near ZERO ohms unless theres a burned or loose or carboned or burned termination. Many cheaper meters arent very accurate at extreme low ohms values like 0 to 5 ohms. If you have a good battery cable Id expect it to read 0 0hms. NOTE an ohm meter passes low current and an item may read 0 ohms on a meter HOWEVER it may still be bad cuz when you pass several hundred amps through it (like when cranking an engine) its only then a major voltage drop happens across a carboned or loose connection. JUST CUZ A CABLE READS 0 OHMS DONT MEAN ITS NECESSARILY A GOOD CABLE!!!!!!!!


Sooooo looks for an R or Ohms or Rx1 or Rx10 etc scale on the meter face,,,,,,,,isolate a device so not a bunnch of other wires and possible circuit paths to it,,,,,,,,,,connect the leads to each end,,,,,,,MEASURE THE OHMS OF RESISTANCE,,,,,,,and short sections of copper wire or big cables should read near 0.

Call again if neeeded but were getting ready to head south and I will be on my cell phone in days to come FLORIDA FLYWHEELERS is soon ya know.

PS take it to the HS where you help out and let those young "dudes" help you.....If its digital they can if analog maybe not???

John T

JohnT,
You have a simpson 260? Is it a series 1? That meter must be OLD. The upside to the old analogs is you can zero the ohm scale.

The new digitals, at least the ones I get FREE from HF, there is no zero adjust. So when you short the leads together you may get anywhere up to 5 ohms showing, instead of zero.

When measuring ohms of something like a fuse, I'm only concerned if there is an open or continuity. The exact resitance isn't really important.

The upside to a digital voltmeter is you don't have to worry about polarity like you would with your simpson.

Have a safe trip. Enjoy Florida's liquid sun shine.
George

George, I too have an old Simpson 260. The last time I tried to use it, it wouldn't work. I suppose the switch contacts are corroded from lack of use.

The reason the old analog units had a zero adjustment wasn't so much to allow for the lead resistance as it was to compensate for the battery condition. They don't have a real stable current source (I think it's just a resistor), so the zero would be all over the map.

Something to be aware of with digital units is that the "continuity" or "diode check" scale is NOT a resistance measurement! It actually displays VOLTS, not OHMS. The reason for this is that a good diode has a forward bias voltage of around 0.7 volts. A lot of folks use the diode check range, see a reading of less than 1.0 and assume the resistance is zero. NOT SO! When in doubt, double-check the actual resistance.

I have two 260s. Got one when I first started field work 45 years ago. Only bad thing about them. They gain weight the more you have to drag them around.

THANKS TO ALL John T have a good trip George thanks i sent a fordward just respond with your phone number Hey old I don't know you but thanks for help and also your military service

Mark, Another problem with a digital is temperature. When they are in a cold truck, they will lie to you, shocking. I carry an old analog radio shack meter to get a second opinion. Also use an AC detector that looks for magnetic radiation to tell me when the wire is hot. Can't be too safe. Them a final check for AC, I take two screwdrivers and make a short to ground. Have a few screwdrivers with parts of the tip missing.
George

Never had any problems with a digital checking diodes. Just look for a forward and reverse bias with meter.

In case you missed the input: "depending on the battery condition" in one of the replies.....I'd loose this going back to give credit to the author, you need to heed that comment.

The internal battery is not required to measure other things, but for resistance readings you need to get current from somewhere to run through whatever you are ohm testing so that you can get deflection on the meter........the battery must be in good condition.

As they age you have to continuously re-zero the meter and finally you can't zero it at all. Other thing, as mentioned is that there is some resistance to the leads but putting them together and then zeroing an ANALOG meter (one with a moving needle) removes that error that occurs with digital meters which don't have a zeroing mechanism as such.

Mark

Agree - should be girls

MarkB got me to looking. This will help.
Electrical testing

This is why I keep asking trouble shooters to report battery post voltage while cranking. And voltage between the starter body and the main post while cranking.
The voltage difference will indicate the high resistance cable or connection.

What can I say that was some 38 or so years ago that I learned that in Navy electronics A school. Some how one forgets over time and when you do not use it any more you forget a whole lot easier. Did my electronics A school on Damneck VA which is very close to Virginia Beach VA

I always try to do my best to if and when I can. Plus since I was a former Navy Electronics Tec I figured I could give it a pretty good go and at least get you in the ball park

What can I say been 38 years since I learned that so I guess I have a bit of a reason to forget some of it LOL

Next question, is, do you still remember the horse for trig for Sine,Cosign, and Tangent?????

No shoot I do not remember any more what E=MC squares is. I can still count in Binary and octal and understand that if one really thinks about it a computer only knows off and on and counts only in binary but converts it to what we understand better. And I do remember something called the right hand and left hand laws of current or some such thing.

If you are looking for voltage drop then use the DC voltage part of the meter and check the drop at the end of the cable. Check with cable off then check with cable hooked up this will tell if you are getting enough voltage to start the engine. It should be around 10 volts on a 12 volt system. Close to 5 on a six volt. There should be no drop with cable off of motor.
Walt

Forgot check operating voltage at both ends of the cable and at the battery to see where the lose is.
Walt

Forgot check operating voltage at both ends of the cable and at the battery to see where the lose is.
Walt

All Sailors Take Chances. For Sine, cosine, tangent. Somebody help me remember how it works. Dave going back to 65.